/**
 * @author 35326
 * @date 2021/3/9 17:30
 */
public class _29 {
    public static void main(String[] args) {
        B b=new B();
        System.out.println("40+50的结果是：" + b.sum(40, 50));
        System.out.println("40-50的结果是：" + b.sub(40, 50));
    }
}

abstract class A{
    abstract int sum(int x,int y);
    int sub(int x,int y){
        return x-y;
    }

}

class B extends A{
    int sum(int x,int y){
        return x+y;
    }
}
